AUGUST Night Skies
AUGUST NIGHT SKIES OVER TANZANIA
Dr. N. T. Jiwaji
ntjiwaji at yahoo dot com
This month’s name signifies ‘grand’, impressive, ‘imperious’, derived from the Roman Emperor Augustus. And the skies live up to this name in astronomy also, with an impressive and grand events and shows in store. These include two eclipses, two New Moons, planetary line ups and close encounters.
The first of the month is the first New Moon, which brings a total solar eclipse. The eclipse begins in Canada and ends in the middle of China. Unfortunately, none of it will be visible in Tanzania.
16th of August will be more exciting for us with a Full Moon ushering in a partial lunar eclipse centered just off southern coastal tip of our country. Mid-eclipse will hence be close to midnight at 00:40 am with 81percent of the Moon being covered by the Earth’s shadow. This eclipse will begin at 9:23pm with a light almost unnoticeable penumbral shadow. At 10:36pm the dark, umbral shadow of the Earth will begin to creep over the Moon’s disk to cover it eventually by 81% at 00:40 The shadow will then slowly slide away by 01:45am (of 17th). The last penumbral part will end at 02:57am. So to watch the visible part of the eclipse, you will need to be ready before 10:36pm and can go on upto 01:45am.
August also begins with a line up of seven solar system bodies in the east just after sunset. In the order they are: Moon, Sun, Mercury, Venus, Saturn and Mars. At sunset Mercury will be closest at 9 degrees above the Sun while Venus will be 15 degrees, Saturn 24 degrees and Mars 38 degrees above the Sun, making all just within the visibility limit soon after sunset. The thin crescent Moon will be shifting its position from one to the other day by day from 1st to 4th when it will be closest to Mars. On 9th and 10th they will appear in an almost perfect line in the sky called the ecliptic which can be extended upto Jupiter on the other side of the sky.
These planets will also be jostling for position shifting among themselves and relative to the fixed star Regulus in Leo, which provides a steady reference among the ‘wandering’ planets. On 15th August, Venus, Mars and Saturn come close together to form a thin triangle with Venus at the top and Mercury and Saturn about 2 degrees below forming its base less than one degree apart. Note that one finger held at an arm’s length is about three quarter of a degree so you can estimate the separations in the sky using this method.
The Moon comes close to the red star Antares in Scorpio on 10th. On 13th an almost full Moon will be close to Jupiter by about 3 degrees (four fingers), similar to the position it had last month on 17th during the spectacular pass of the International Space Station.
Early in the evening of the lunar eclipse on 16th watch Venus, Mercury and Saturn close together form a gentle arc. On 20th and 21st, Mercury and Venus will be very close together less than a degree apart. The month ends with a second New Moon on 30th.
Among the evening constellations are the long, winding Scorpio, and Sagittarius the archer. The Southern Cross lying on its side close to the southwestern horizon points south. In the north you can make out Cygnus the swan as a cross with the bright Deneb (A) at its tip. Among the bright stars you can try some with famous names. These are, from west to east, Spica (B) in constellation Virgo, Arcturus (C), Alpha (D) and Beta Centauri (E) the two bright stars in the southern skies that point to the Southern Cross, the red star Antares (F) in the neck of Scorpio, Vega (G), Altair (H) and Deneb (A) all in the north and Fomalhaut (J) just rising in the east at 8 p.m
The Perseid meteor shower peaks on 11th/12th August when more than 50 meteors per hour could be seen after midnight in the northeastern sky. Since this meteor activity is usually spread over several days around the peak, go out on a moonless night to see a good number of shooting stars.
The International Space Station can be best seen on 17th August around quarter to seven rising in the north west and rising to nearly 70 degrees and setting in south east about five minutes later. Confirm the exact timing if you have access to the Internet at http://spaceweather.com/flybys and entering your location.
A note of caution before we end: Be aware of emails this month predicting Mars will be seen as big as the Moon. This is an old story with a lot of salt added that refuses to die out since closest approach of Mars in 2003. At the moment Mars is in retreat!
END